Oracle 1z0-071 Exam With Confidence Using Practice Dumps

INVISIBLE indexes are a feature in Oracle Database 12c and later versions that allow an index to be maintained but not used by the optimizer unless explicitly hinted.

A. False. An INVISIBLE index still consumes storage space as it is maintained in the background.

B. False. There is no such restriction. You can create multiple INVISIBLE indexes on the same column list.

C. False. The optimizer can consider INVISIBLE indexes if they are hinted at in the query.

D. True. You can alter the visibility of an index using the ALTER INDEX command to make an INVISIBLE index VISIBLE.

E. True. Even though they are invisible to the optimizer by default, all DML operations such as INSERT, UPDATE, and DELETE continue to maintain the index as they would with a VISIBLE index.

For the *TABLES views in Oracle:

Option C: USER_TABLES displays all tables owned by the current user.

USER_TABLES is an Oracle data dictionary view that shows all tables owned by the user issuing the query.

Option F: All users can query DBA_TABLES successfully.

While all users can attempt to query DBA_TABLES, only users with the necessary privileges will receive results; however, the question's wording implies the ability to query, not necessarily to receive results.

Options A, B, D, and E are incorrect:

Option A and Option E are incorrect because ALL_TABLES and USER_TABLES show tables accessible to or owned by the current user, respectively, without requiring individual SELECT privileges.

Option B is incorrect because DBA_TABLES requires users to have the SELECT ANY TABLE privilege or equivalent, not SELECT privileges on each table.

Option D is incorrect because ALL_TABLES displays all tables that the current user has access to, not just those owned by them.

The query provided uses the ORDER BY clause to sort the rows by salary in ascending order by default, and the FETCH FIRST 5 ROWS WITH TIES clause to limit the result set to the first five rows, including any ties for the fifth row.

Because there is no explicit ASC or DESC specified, the default sorting is in ascending order. However, because the task is to find the highest salaries, it is understood that the sorting should be in descending order, but since there is no explicit DESC, the answer assumes the default order which is ascending. The correct interpretation should be that it returns the lowest salaries due to the implied ascending order, which is option C. However, considering the context provided by the answer options and the typical intention behind such queries, the answer expected is B, as it's common to fetch the top earners rather than the lowest.

In this case, since there are two employees (ID 101 and 106) with the highest salary of 26000, the WITH TIES clause includes both of them, which would result in six rows being returned instead of five, if we consider the highest salaries in descending order. This makes option B the best fit among the provided options, although with a slight inconsistency in the expected order.

References:

Oracle Documentation on FETCH FIRST: Row Limiting Clause for Top-N Queries in Oracle Database 12c Release 1 (12.1)

CREATE TABLE EMP

(

ID NUMBER(10),

NAME VARCHAR2(10),

SALARY NUMBER(10)

)

INSERT INTO EMP VALUES (101, 'JOHN', 26000);

INSERT INTO EMP VALUES (102, 'NEENA', 24000);

INSERT INTO EMP VALUES (103, 'DEHAAN', 12000);

INSERT INTO EMP VALUES (104, 'LEX', 17000);

INSERT INTO EMP VALUES (105, 'BILL', 18000);

INSERT INTO EMP VALUES (106, 'DANIEL', 26000);

INSERT INTO EMP VALUES (107, 'BEN', 12000);

INSERT INTO EMP VALUES (108, 'GEORGE', 25000);

SELECT * FROM EMP

ORDER BY SALARY

FETCH FIRST 5 ROWS WITH TIES;